Thread: running lean????

i need sum help i bought this car last summer. ran fine all year now haveing sum problems its like its breaking up alittle but not all the time. i pulled the plugs tonight an there a whiteish color like its running lean. an i dont beat on it an im only running 8lbs of boost. fuel pressure is at 45 psi new 300zx gas filter plugs, cap rotor, wires, jim wolf ecu, t25. can really use sum help on where to start.

Do you have a wideband O2 setup? You're probably going to hear that question a lot, but it's pretty much a necessity really. It's about the only way you will know your air/fuel ratio for certain.

That aside, JWT tunes usually run a little rich. Have you checked your injectors and injector seals? Could be fuel pump related also. FPR?

What spark plugs, and what is the gap set to? My side electrodes on my BKR7E's are a little more white than normal, but I run a fairly large gap for boost. More than most would run anyway, but it works for me. I'm also running just a little rich.

i ordered a wide band it should be here tomorrow, my fpr is around 42psi with getting on the throttle. im running ngk BKR6E's. as far as i kno there is a walbro 255 in the car. an it has a set of whiteish 370s inj which i was told were from a q45 but i do hace a set of purple 370s but the pintle caps are broke and afraid to put them in. do you know if i take them off will it make a difference in the spray patteren? thats the white plastic peice at the tip of the inj. an help will be grateful thanks

As far as I know, some turbo applications use the bkr6e's as stock. But you might be safer with some 7e's, or a plug in that same heat range. Just depends on if you plan on staying at 8 psi max, and how much you get into boost. Did you gap your plugs before installing them? Don't trust that they were correctly gapped at the factory. I've pulled new plugs out of the box that ranged from +-.015 gaps.

I would suggest checking your injectors. Search on how to check your injector flow rate, or how to check if they are functiong properly. You may have one on it's way out, or plugging. May not hurt to check your fuel pump flow rate either. May not be the problem, but it's good to know.

I've heard some people say the plastic peices on the end of the injectors will affect spray pattern, and some that say it doesn't. I've never checked myself. I do know that 3 out of 4 of the injectors I have in right now are missing the little arm peices that extend over the pintle, but the plastic cap is still there. I've had no problems.


The only pic I had was the 370's I used to use. But some of them were beat up too. You can buy replacement pintle caps pretty cheap online.

Once you get your wideband installed, you'll know for sure what your a/f ratio is. It's a lot easier to diagnose conditions with it.

I don't claim to be the most knowlegable, but hopefully someone else will chime in that has experienced this before, or has corrected a problem like this.

thanks for the info ill be sure to check everything tomorrow an ill let u know what i come up with thanks